1. Field of the Invention
The present invention concerns a winding device and a method for winding a material web on a reel. The winding device includes a feed roll, a carrying frame, e.g., a carrying drum and a perforated support belt, and a reel upon which the material web is wound. A vacuum may be applied to hold the material web to the carrying fame. The method of the present invention relates to introducing the material web over a feed roll, guiding the material web by a perforated support belt over a suction carrying drum, and forming a winding nip (gap) between the carrying drum and a reel upon which the material web is wound.
2. Discussion of Background Information
EP-Bl-0 658504 discloses a winding device having a carrying drum with internal suction. The winding device may be used at the end of a machine for producing or refining a material web or may be used to rewind an already wound roll. Such a machine may be a paper machine. During operation, problems may occur particularly when the material web or a leading end of the material web, also referred to herein as the threading tip, is fed into a winding arrangement. Thus, it is conventional to have lead cables, blow plates, vacuum belts, and/or the like to transport the leading end of the material web to the carrying drum, after which the leading end may be guided around the carrying drum. Then, a doctor blade, such as a blow doctor, may remove the leading end of the material web from the carrying drum, and the leading edge may be guided with a blow wedge or the like, or may be diverted with a guide plate, into a pulper. The paper web is then broadly and continuously diverted into the pulper by, for example, a guide plate with a blower. Thereafter, the material web may be separated, i.e., cut, with a gooseneck, belt, knife, water jet, and/or the like and guided onto an empty reel which is made available. Sometimes the automatic feeding of the special strip-type leading end or of the entire material web on an empty reel or on an already wound roll may become uncontrollable. This often occurs with higher machine speeds and with grooved or perforated carrying drums, which are not provided with suction.
FIG. 1 depicts a prior art winding device 10. In device 10, a winding nip (gap) 18 is formed between carrying drum 12 and an empty reel 16'; three web paths, A, B and C are shown, with path A being desired and paths B and C being undesired. In desired web path A, the leading end of material web 14 is first released from carrying drum 12 by a doctor blade 20 and diverted into pulper 22. In web path B, the strip-type leading end of material web 14 or the entire width of material web 14 is guided over carrying drum 12 and wound directly downstream from winding nip (gap) 18 in an incontrolled manner upon empty reel 16'. In web path C, there is uncontrolled automatic feeding onto an already wound reel 16.
By providing a vacuum in carrying drum 12, the guidance of the usually strip-type leading end of the material web or the material web itself is controlled up to a discharge zone where a doctor blade 20 is provided so that automatic feeding upon empty reel 16' (web path B) may be avoided However, with a vacuum in the carrying drum, the web pickup by the doctor blade is made more difficult, and the material web may possibly feed in an uncontrolled manner onto a wound roll as in web path C.
Also, it is problematic in the known designs to have the web removed from a carrying drum with a coated surface (e.g. SiC), soft coating, and/or surface structures, such as, in particular, ridges, V-shaped grooves, or the like, because doctor blade contact is not possible. The leading end, i.e., the threading tip of material web 14, or the entire width of material web 14, must then be freed from the carrying drum with a blow knife, which also makes guidance of the web into the pulper more difficult. Moreover, with internal vacuum carrying drums whose interiors are completely subjected to a vacuum, it is possible for air to inadvertently penetrate into the part of the carrying drum not contacted by the web, which results, in particular, in relatively high energy consumption. On the other hand, carrying drums with inside seals have the disadvantage that the carrying drums have to be dismantled in order to change seals.